It sends an impulse back to the cell body of a neuron
<span>Cardiovascular / Circulatory system: ...Digestive system / Excretory system: ...Endocrine system: ...Integumentary system/ Exocrine system: ...Lymphatic system / Immune system: ...Muscular system/Skeletal system: ...Nervous system: ...<span>Renal system / Urinary system:</span></span>
Answer:
Answer: The collection of all the genes and the various alternate or allelic forms of those genes within a population is called gene pool.
They are sandwiched between two layers of heads. Recall that the heads are hydrophilic therefore they will always be on the outside and the tails are hydrophobi therefore they willl always be away from water, there fore sandwiched. I'm a bio major, hope I helped :)